he race may be dug to a
distance of a rod or so inshore, and then be permitted to cut its own
course along the bank, preventing the water escaping back to the river
or brook before the site of the power plant is reached, by building
suitable retaining embankments. The race should be of ample size for
conveying the water required without too much friction. It should end
in a flume constructed stoutly of timbers. It is from this flume that
the penstock draws water for the wheel. When the wheel gate is closed
the water in the mill pond behind the dam, and in the flume itself
should maintain an approximate level. Any surplus flow is permitted to
escape over flushboards in the flume; these same flushboards maintain
a constant head when the wheel is in operation by carrying off what
little surplus water the race delivers from the pond.

[Illustration: Detail of bulkhead gate]

At some point in the race or flume, the flow should be protected from
leaves and other trash by means of a rack. This rack is best made of
1/4 or 1/2-inch battens from 1-1/2 to 3 inches in width, bolted
together on their flat faces and separated a distance equal to the
thickness of the battens by means of iron washers. This rack will
accumulate leaves and trash, varying with the time of year and should
be kept clean, so as not to cut down the supply of water needed by the
wheel.

The penstock, or pipe conveying water from the flume to the wheel,
should be constructed of liberal size, and substantially, of two-inch
chestnut planking, with joints caulked with oakum, and the whole well
bound together to resist the pressure of the water. Means should be
provided near the bottom for an opening through which to remove any
obstructions that may by accident pass by the rack. Many wheels have
plates provided in their cases for this purpose.

The tailrace should be provided with enough fall to carry the escaping
water back to the main stream, without backing up on the wheel itself
and thus cutting down the head.

It is impossible to make any estimates of the cost of such a
water-power plant. The labor required will in most instances be
supplied by the farmer himself, his sons, and his help, during times
when farm operations are slack.

_Water Rights of the Farmer_

The farmer owns the bed of every stream not navigable, lying within
the boundary lines of the farm; and his right to divert and make use
of the water of such streams is determined in most st